Tower - Region - Continent - Globe: Bridging the gap between flux towers and flasks

1
Tower - Region - Continent - Globe Bridging the
gap between flux towers and flasks

• Goals
• Merge our mechanistic understanding of
  terrestrial C dynamics at the tower scale with
  our understanding of the global CO2 budget
  obtained from the flask network.
• Understand the mechanisms that govern changes in
  the atmospheric CO2 budget at seasonal to annual
  time scales, and regional to continental spatial
  scales.

2
Contributors

• M.P. Butler, K.J. Davis, M. Hurwitz, D. Ricciuto,
  W. Wang, and C. Yi, The Pennsylvania State
  University
• B.D. Cook, University of Minnesota
• P.S. Bakwin, NOAA/CMDL
• A.S. Denning and colleagues, Colorado State
• J. Berry, B. Helliker, Carnegie Institute
• B. Balsley, J. Birks, M. Jensen, and K. Schultz,
• University of Colorado
• Support NIGEC, DoE-TCP, NASA, NSF
• Related talks Schmid, Wofsy, Hollinger,
  Denning, Keeling

3
Methods for determining NEE of CO2 Methods for
bridging the gap
Upscale via ecosystem models and networks of
towers.
Move towards regional inverse modeling
4
Atmospheric approaches to determining NEE of CO2
Time rate of change of CO2
Mean transport
Turbulent transport (flux)
Source in the atmosphere
Average over the depth of the atmosphere (or the
ABL)
F0C encompasses all surface exchange Oceans,
deforestation, terrestrial uptake, fossil fuel
emissions.
Inverse study Observe C, model U, derive F Flux
study Observe F directly
5
Progress

• AmeriFlux towers can be used to monitor
  continental boundary layer CO2! Downscale
  inversions. dC/dt, dC/dx
• Future Create this network. Complement tall
  towers, airborne profiles, satellite CO2.

6
Surface layer towers can (should!) be used to
monitor continental CO2
7
The seasonal amplitude of the gradient in
CO2 between the continental ABLand the marine
boundary layer is large. Surface layer -
mid-ABL difference (1 to 2 ppmv) does not
overwhelm this signal.
8
Progress

• Coherence among continental-scale, annual and
  seasonal flux anomalies exists and is reflected
  in the atmospheric CO2 network. Upscale fluxes.
  F0C Downscale inversions (in time).
• Future Continue analyses. Incorporate flux
  data into inversion models. Explain 1998
  anomalous increase in atmospheric CO2?

9
Spatial coherence of seasonal flux anomalies
A similar pattern is seen at several flux towers
in N. America and Europe. Three sites have
high-quality CO2 measurements data at
Fluxnet (NOBS, HF, WLEF). The spring 98 warm
period and a later cloudy period appear at all
3 sites.
10
Detection of the spring 98 anomaly via oceanic
flasks?
2 Alaskan flask sites have slightly higher CO2
in the spring of 98. Mace Head, Ireland shows a
depression of CO2 in the spring of
98. Potential exists to link flux towers with
seasonal inverse studies.
11
Progress

• ABL budgets are being used to derive regional,
  daily NEE of CO2. Downscale inversions. COBRA,
  Powered parachute, tower-based.
• Lagrangian budgets. COBRA.
• Advection in the continental ABL CO2 cannot be
  neglected on monthly time scales. U dC/dx.
• Synoptic events drive advection of CO2.
  U dC/dx.
• Promising results using H2O - CO2 similarity.
  Helliker and Berry.
• Future Continental CO2(x,y,z) network is
  required. Critical method for model validation
  at large time and space scales.

12
ABL budgets - regional inverse studies
13
CO2 advection in the continental ABL
CO2
Si (F0C.Dt)i
14
CO2 advection in the continental ABL
15
Synoptic variability in CO2
16
(No Transcript)
17
Regional fluxes from H2O - CO2 similarity
From Helliker and Berry, poster.
18
Progress

• The rectifier effect - a major source of
  uncertainty in transport models - is being
  quantified via observations. COBRA. Powered
  parachute. WLEF ABL radar deployment. Improve
  inversions. FzC and z.
• Future Examine conclusions with more
  continental profile data, including airborne data
  and additional AmeriFlux/Fluxnet sites. Validate
  tower-based assessment with airborne profiles.
  Quantify transport between the continental ABL
  and the marine boundary layer.

19
Rectifier is underestimated in the day?
WLEF tower ABL radar vs. Denning 1995 model.
20
Rectifier is overestimated seasonally?
WLEF tower ABL radar vs. Denning 1995 model.
21
Research needed

• Construct a continental CO2 network. Make
  AmeriFlux towers part of this network. Move
  towards regional inversions and assimilation of
  flux and mixing ratio data into coupled
  ecosystem-atmosphere models.
• Increase the AmeriFlux/Fluxnet database. Include
  CO2. Report data! Common formats/QC!
• Continue to analyze spatial patterns in flux
  measurements to link to the mechanisms of global
  CO2 variability.
• Airborne flux - modeled flux - ABL
  budget/regional inversion joint projects.
• Conduct the North American Carbon Program.